How to remove personal data from a blend file
As far as I know, there is no way to strip this information from a .blend file without editing the file itself as you have done and that has its own set of cons.

Option 1

Work at the root directory of your system. ie. C:/personal_folder/ or on a portable medium. You say you don't have any images or such attached so this shouldn't log anything private such as your username or any other personal paths provided you don't import anything and all you have is a model.

Option 2

Export to another format and reimport back into Blender. Exporting to a simple format such as .obj will only export mesh data (if all you have is a mesh) and same goes for importing it back. I did this with a file saved on my desktop and the only instance I could find with personal info was the location to the file. Use this with method 1 for optimal results.

As it addresses your other privacy concerns, being identified as to what OS you're on is fairly useless information and if you're sharing a file here, you might even be asked what os you are running so provided that no personal paths are included you should be fine.